Air operated tool and piston therefor



Oct. 22, 1963 R. E. POWERS AIR OPERATED TOOL AND PISTON THEREFOR INVEN TOR. 3/67/9610 I. POM/A766 Filed Sept. 17, 1956 E6. 12

United States Patent 3,197,584 ABE OPERATED T691. AND PISTON Ti-EREFOR Richard E. Powers, Monterey Parir, Calif, assignor to Powers Wire Products Company, Inc a corporation of California Filed Sept. 17, 1955, Ser. No. 610,118 2 @iaims. (Cl. 9285) This invention has to do with an air operated tool and piston therefor and is particularly concerned with the construction of a piston that is operable to reciprocate in a cylinder, it being a general object of this invention to provide a most effective and reliable tool involving a cylinder and piston mechanism.

Various problems arise in the erated tools, for example in tools for driving fasteners such as staples or the like. Tools of the character referred to involve a staple guideway adapted to direct the movement of a staple driver blade. The said blade is ordinarily connected rigidly or driven positively by a piston operating in a cylinder, the piston being actuated by fluid entering the cylinder under pressure. Because the driver blade is a slender elongate element it is inherently flexible and bends or warps when driving stresses are applied thereto. Due to the normal warpage of the driver blade it is necessary to increase its length in order to compensate for said warpage in order to realize a full and effective stroke from the tool. Punther, it is often desired to increase the length of the driver blade so that it projects from the head of the tool at the end of the work stroke in order to obtain full driving action as the tool recoils away from the work. When the piston and the driver blade are in a normal unactuated position, or at the lower end of the tool (-see FIG. 1), a driverblaide of the character thus far described would ordinarily pro ject from the head of the tool. It is obvious that a projecting drive-r blade is detrimental since it will be dragged over work damaging and injuring said work and the blade itself.

Another problem arising in the building of fluid operated tools of the character under consideration is the problem of obtaining a rapid and effective stroke of the piston operating in the cylinder. Ordinary pistons employed in tools of this type are essentially a single relatively heavy unit of construction connected directly to the driver blade with the result that acceleration is relatively slow and with the result that the entire weight of the piston must be damped at the end of the work stroke and to the end that a considerable amount of the piston weight cannot be employed in driving the blade. That is, the inertia of the piston is ordinarily absorbed by snubber means, thus subtracting from the driving force required to render the driver blade effective in driving staples and the like.

It is a general object of this invention to provide a most effective tool for driving staples and the like which inherently overcome the objections above referred to.

An object of thisinvention is to provide a tool of the character referred to wherein the driving blade is re tracted after completion of the work stroke and is prevented from projecting from the head of the tool when the tool is in the unactuated condition. The blade of the tool of the present invention is, therefore not vulnerable and will not be dragged across the work to damage the same.

It is an object of this invention to provide a piston for a tool of the character referred to that can be accelerated rapidly in order to effect a most efjcient work stroke having maximum driving power.

It is still another object of this invention to provide a piston for a tool of the character referred to that is damped without afiecting the driving power of the driver blade.

building of fluid op- 3,107,584 Patented Oct. 22, 1963 It is also another object of this invention to provide a piston for a tool of the character referred to that is independently damped and which operates to drive the blade in one direction only. I provide independent damping means for the piston and driver blade whereby the inertia of the driver blade is not retarded by the damping or snubbing of the pisto An object of this invention is to provide a simple and effective piston construction for tools of the type under consideration resulting in a structure or tool that is simple to make and which is easily operated and economical to maintain. I p

The various objects and features of my invention will be fully understood from the following detailed description of a typical preferred form and application of my invention, throughout which description reference is made to the accompanying drawings in which:

'FIG. 1 is a side sectional view of a fastener driving tool that incorporates the piston of the present invention. FIG. 2 is an enlarged sectional view of a valve means that I prefer to employ. FIG. 3 is an enlarged sectional view of the piston that I provide, showing the parts thereof in a normal unac-tuated position. FIG. 4 is a view similar to FIG. 3 and showing the manner in which the parts of the piston operate. FIGS. 5 land 6 are sectional views taken as indicated by lines 5-5 and 6-6 on FIGS. 3 and 4, respectively, and FIG. 7 is a sectional view taken as indicated by lines 7-7 of FIG. 1.

The air operated tool and piston thereof that I have provided may be in the form of a stapling gun and, therefore, in the drawings I have illustrated this type of tool. "It is to be understood, however, that the present invention is not limited to this particular kind of tool and may be employed in connection with various tools having a cylinder and piston driving means. The tool as illustrated in the drawings is adapted to be handled manually and involves, generally, a frame A having a body portion 10 and a handleor grip portion 11, a head B carried by the frame A and adapted to direct fasteners into a piece :of work, a magazine C for handling a supply of fasteners such as staples and cooperating with the head B so that the staples are received and handled by the head, a driver blade -B, a guide means E for handling the staples and accommodating the driver blade D so that it is continuously guided by the head B, latching means F adapted to cooperate with and control operation of the driver blade D, a piston G having driving connection with the driver blade D, a damping means H for the piston G, and valve means I adapted to control the supply of fluid under pressure to actuate the piston G.

The frame A carries the various elements of the tool, and is shaped to be conveniently handled by a person. The frame A involves, generally, the body portion It and the handle or grip portion 11. The body portion 10* is a simple elongate part having a cylinder 12 extending longitudinally thereof and having an opening or passage 17 extending longitudinally through the lower head end thereof at one end of the cylinder 12, and is characterized by a flat front face 13 and a recess 14. The front face 13 is at the forward end of the body and is normal to the longitudinal axis of the body, while the recess 14 is in the form of a fiat seat spaced laterally of the axis of the body and parallel therewith. The said seat extends rearwardly from the face 13 to a shoulder 16 where the passage 17, that is rectangular in cross sectional configuration, opens to the exterior of the body. The shoulder =16 is normal to the longitudinal axis of the body.

The handle or grip portion 11 is provided to give the person handling the tool a convenient means to hold the tool and is a simple grip of ordinary construction that projects from the body 10. In practice, the grip 11 may be substantially normal to the axis of the body and may project therefrom as clearly shown in FIG. 1 of the drawings. In structures of the type under consideration, it is common practice to provide a fluid pressure supply connection 18 at the grip 11, such asa pneumatic hose or the like, and also to include a control means at the grip 11. It is to be understood that any suitable fluid pressure supply can be provided without affecting the present invention. When compressed air is employed, as in the case illustrated, the hose of the power connection 18 is attached to the grip 11 through a quick disconnect 2ft and the valve means I is under control of a finger operated trigger 21.

The head B is, in effect, an extension of the body of the frame A and is provided to receive and deliver fasteners such as staples to the work being acted upon by the tool. The head B is carried by the body 10 in the recess 14 and is provided with a longitudinal guideway 22 that extends through and opens at the ends of the head B. The head B has a bottom face 23 engaged with the seat of recess 14, it has a rear end face 24 normal to the axis thereof and engaged with the shoulder 16, and it has a front end face 25 engageable with the work.

In the particular form of the invention shown, the guideway 22 is adapted to handle fasteners or staples S that are U-shaped and formed of wire, or the like, having a pair of sharpened ends (see FIG. 7). The staples referred to are substantially elongate with straight parallel shanks joined by a curved back. It will be apparent how the guideway 22 can be proportioned so that it will readily pass the staples with clearance and will act upon the staples to guide them as they are delivered through the head B and from the tool. The guideway 22 is a continuation of the passage 17 above described and guides the driver blade of the tool as well as the staples S that are handled thereby.

A fastener or staple receiving opening 32 extends laterally through the head B, which opening enters the bottom face 23 of the head and opens intothe passage 22 so that the staples S fed to the head B are properly guided and aligned with the passage 22 before they are engaged by the driver blade D of the mechanism. The passage 22 has a staple guiding portion at the front of the head B of suflicient width to freely pass a fastener or staple handled by the head B, and the passage 22 has a blade guiding portion rearward of the first mentioned portion that is of increased width in order to accommodate the relatively large plunger or driver blade D.

The magazine C is adapted to handle a supply or stack of fasteners or U-shaped staples S and involves, generally, a case 35 carried by the frame A, a guide 36 within the case 35, a follower 37 adapted to advance the fasteners or staples, and a feed spring 38 yieldingly urging the follower toward the head B. The case 35 is carried by the front face of the body 10 and is an elongate part that projects laterally from the frame A. The case is a shell like part and the guide 36 is a core-like part that is coextensive with the case 35 and is carried between the side walls thereof. As shown, in FIG. 1 of the drawings, the case 35 and guide 36 are shaped so that a longitudinal passage 40 is formed, which passage conforms in general configuration to the U-shaped staples S which are han dled by the head.

The guide 36 enters the fastener or staple receiving opening 32 and terminates in a flat end 39 that occurs in the plane of the bottom wall of the guideway 22. The follower -37 conforms with the configuration of and is slidably carried in the passage 40 and is yieldingly urged toward the head B by the feed spring 38. Means is provided to prevent the follower 37 from entering the guideway 22. The fasteners or staples S are inserted into the magazine C through the open top thereof by simply en gaging them over the guide 36 ahead of the follower 37 tensioning the spring 38. As clearly shown in FIG. 1, a spring biased latch secures the follower 37 in a retracted position when desired, thus facilitating insertion of the fasteners.

The driver blade D is essentially a slender elongate part rectangular in cross sectional configuration and terminates at its forward end in a flat fastener or staple driving face 45. The blade D has a staple driver portion at the forward end thereof which occupies the staple guiding portion of the guideway 22 when the driver is in the advanced position (see FIG. 1), and also has a stem that is guided by the blade guiding portion of the guideway 22. As shown, the blade D is provided with an inclined cam or face 48 that is pitched upwardly and rearwardly and which is provided to shift the guide means E hereinafter described.

The guide means E is in the form of a closure or gate that is pivota-lly carried by the head B so that it normally substantially occupies the top of the head B. As shown, the gate 5% is elongate and shiftably carried by the head B by means of a pivot pin 51. The gate 50 normally occurs in a position where it forms a continuation of the guideway 22. As shown, the gate 50 is provided with a cam face 49 that cooperates with the cam face 48 above referred to provided on the driver blade I). By providing the cooperating cam faces 48 and 49, the gate St is shifted or moved to the position shown in order to allow the driver blade D to advance. A spring 56 is provided to yieldingly hold the gate 50 in a down or normal position where it forms a continuation of the guideway 22 and thereby guides the staples handled by the tool and also guides the driver blade D of the tool. A head construction for a fastener driver of the type referred to is particularly set forth and claimed in Letters Patent No. 2,784,406 issued to Richard E. Powers;

The latching means F that may be employed in tools of the type under consideration is adapted to cooperate with and control operation of the piston G, later described. The means F is provided to couple with and to hold the piston G at the upper end of the cylinder 12 and to release the piston G when sufficient fluid pressure has been established in the cylinder to effect the desired work stroke. The latching means F may involve suitable mechanism to carry out the function referred to without affecting the present invention. For example, the latching means F may involve means adapted to releasably couple to a head 57 that projects from the top of the piston G,

and a pressure responsive release means adapted to re lease the head 57 from the upper end of the cylinder 12. The upper end of the cylinder 12 remote from the head B is closed by a cap 59, the latching means F being threadedly engaged through an opening in the cap for adjustment.

The piston G-that I have provided in accordance with the present invention operates in the cylinder 12 and has driving connection with the driver blade D. The piston G is adapted to drive or move the driver blade D forwardly or downwardly and is adapted to be damped or snubbed separately from the driver blade D. The cylinder 12 is carried by the body 10 of the frame A on the longitudinal axis thereof, and is supplied with fluid under pressure by the valve means I, as hereinafter described. The piston G is freely carried in the cylinder 12 and is actuated to retract and to advance in the cylinder in a manner common to tools of the type under consideration. In the particular tool illustrated throughout the drawings, the ordinary compression return spring is eliminated which is usually provided within the cylinder 12 ahead of the piston to return the piston to a retracted position. The tool illustrated is operated entirely by fluid pressure so that when the trigger 21 of the tool is initially or partially actuated through an intermediate position the piston G is moved to the top of the cylinder 12, and so that when the trigger 21 is fully actuated the piston G is moved through its work stroke to the bottom of the cylinder 12.

The trigger 21 controls the valve means I later described;

As clearly illustrated in FIGS. 3 to 6 of the drawings,

the piston G that I provide is a unit of construction in volving, generally, a piston body X, a driving head Y free of the body X and adapted to be driven thereby, and a head retracting means Z adapted to position the head Y relative to the body X. In addition to the foregoing, the piston G involves means K coupling the driver D to the head Y. The driver blade D above described is rectangular in cross section and has flat sides 60- and a fiat top end 61. The upper end portion of the blade D is coupled to the head Y and receives driving force from the head Y, preferably through engagement with the said top end 61.

The piston body X occupies the inner diameter of the cylinder 12 and is free to reciprocate in the cylinder between the upper and lower ends thereof. In accordance with the invention the body X is light in weight being made of aluminum or of magnesium, or of any light weight material, and is of minimum cross sectional configuration. As shown, the body X is disc shaped having a fiat top 62, a flat bottom 63, and an outer peripheral wall 64. An annular groove or channel is provided in the wall 64 to carry a seal, for example an G-ring type seal R, or the like. A cylindrical skirt 66 depends from the body X forming an integral part thereof to guide the head X and to cooperate with the coupling means K, later described. The skirt 66 is preferably smaller in diameter than the piston G and leaves an annular cavity surrounding the skirt and beneath the bottom 63 to accommodate and cooperate with the damping means H, later described. The skirt 66 is characterized by a cylindrical inner wall 67 concentric with the central axis of the piston G and with the central axis of the cylinder 12. and frame A of the tool. It will be apparent that the piston body X is an extremely simple and light weight part that is inherently easy to accelerate and to decelerate.

The driving head Y is adapted to be coupled to the driver blade D and is free of the piston body X. In accordance with the invention the head Y is formed of a dense heavy material, for example, of steel or the like, and is of the required weight to provide the desired in ertia to drive the driver blade D, as circumstances require. In practice the head Y is housed within the skirt 66 above referred to and is guided thereby so that it is maintained in alignment with the central axis of the structure. As shown, the wall 67 of the skirt 66 guides the head Y relative to the piston body X. The head Y has a flat upper face 7 t to have fiat engagement with the bottom 63 of the piston body X, and it has a depending extension 71 substantially smaller in diameter than the inner wall 67 of the skirt 66 and substantially coextensive with the skirt when in a normal position (see FIG. 3).

The head Y and extension 71 are round in cross section, the body being stepped at the upper end portion thereof presenting a downwardly facing shoulder 73. The outer diameter 72 of the head Y has free sliding engagement with the Wall 67 and the extension 71 clears the said wall leaving an annular chamber that accommodates the means Z. It will be observed that there is no positive connection between the piston body X and the head Y and that the body X is adapted to drive the head Y downwardly.

The head retracting means Z is adapted to normally position the head Y relative to the piston body X, as clearly shown in FIG. 3 of the drawings. In accordance with the invention the means Z is provided to yieldingly urge the head Y into engagement with the piston body X. That is, the means Z presses against the head Y to urge it upwardly so that the top face 70 is held against the bottom 63 with pressured engagement. The means Z may vary in form as circumstances require and is shown as being a simple compression spring 75 engaged between the shoulder 73 on the head and a seat member 76 carried by the skirt 66. The spring 75 is a relatively light spring and is such as to allow for considerable movement of the head when it is compressed.

The seat member 76 is an annular washer like member carried within the wall 67 with some clearance and has I an opening 77 freely passing the extension 71. An inwardly opening groove 78 is provided at the lowermost end portion of the skirt 66 there being a snap ring 79 engaged in the groove and supporting the seat member 76. It will be apparent that the retracting means Z will allow for continued motion of the head Y after the body X is stopped, by compressing of the spring 75 which acts separately to damp the movement of the head Y.

The means K that I provide for coupling the driver blade D to the head Y may he any suitable means for establishing a positive connection between these two elements so that they operate together as a unit. In the case illustrated, the head Y has a slot shaped recess 80 provided therein and entering the head extension from the lower end thereof. The slot 80 is vertically disposed and extends diametrically of the head intersecting the central axis thereof. As shown, the slot 84) terminates in a flat bottom 81 adapted to have flat seating engagement with the top end 61 of the blade D. The driver blade D slidably enters the slot and one or more pins 82 are passed through the head and blade, coupling the two elements together as a unit.

' The damping means H is provided to decelerate the body X of the piston G and damps or snubs the piston at the end of the work stroke. The damping means H is in the form of a snubber 85 and is shown as a body of resilient material, such as rubber or the like, carried 'within the cylinder 12 and supported by the lowermost head thereof. In accordance with the invention, the snubber 85 is a circular ring shaped part or body that is held in Working position by the walls of the cylinder 12 and which surrounds the driving blade D with substantial clearance. The depending skirt 66 of the piston G enters the snubber ring after which the bottom 63 of the piston engages the top 86 of thesnub ber to compress it. The top 86 of the 'snubber 85 is reinforced by a ring 87 of metal, or the like, that is engageable with the piston. It will be apparent how the snubber 85 slows and stops advance of the piston body 'X at the lower end of the work stroke.

Thevalve means I that I have illustrated in the drawinrgs (see FIG. 2), is a three position valvemeans, however, it is to be understood that various types of valves or controls may be employed in order to control actuation of the piston G in the cylinder 12. The particular valve that I have illustrated is manuall positioned by movement of the trigger 21 and is constructed so as to exhaust fluid from the upper end of the cylinder 12 and to isolate the cylinder from the fluid pressure supply when the valve is in a normal unactuated position, as shown. The valve has an intermediate position that it passes through as it is manually actuated in which position the valve continues to exhaust fluid from the upper end of the cylinder '12 and in which position the fluid pressure supply is connected to the lower end of the cylinder 12 to operate the piston G toward the upper end of the cylinder. Further, the valve has a fully actuated position that it reaches in which position the valve closes the exhaust from the upper end of the cylinder, opens an exhaust at the lower end of the cylinder, and in which position the fluid pressure supply is connected to the upper end of the cylinder to effect the work stroke of the tool.

The valve means J is preferably formed in and carried by the frame A of the tool and, as shown, is housed Within the grip 11. In the case illustrated the body of the valve is a separately formed element and involves, a valve sleeve 90 that is carried in a recess or bore 91 provided in the grip 11. As shown, the bore M opens at the forward side of the grip 11 and is a straight cylindrical bore termimating in a bottom 92. Fluid handling passages connect the bore 91 with the fluid pressure connection 18, With the outside atmosphere, and with the upper and lower end portions of the cylinder 12. The connection 18 i connected to the bore 91 by a passage 93 (that opens into the bore intermediate the ends thereof, preferably about midway therebetween. The outside atmosphere is connected with the bore 91 by a passage 94 that opens into the bore at the upper end portion thereof and opens to the atmosphere at the butt end of the grip 1-1. The upper end of the cylinder '12 is connected to the bore 91 by a passage 95 that opens into the bore intermediate passages 93 and 94 where they enter the bore. The lower end of the cylinder 12 is connected to the bore 91 by a passage 96 that opens into the bore intermediate the passage 93 and the lower end of the sleeve 90.

In addition to the foregoing connections, an exhaust port 97 is formed by the open lower end of the sleeve 9t) that surrounds the movable element of the valve. The sleeve 90 is suitably ported at 100, 161, 102 and 103 and the shiftable valve element 105 is provided withspaced upper and lower heads 1% and 107 that direct the flow of fluid to control the piston G, as above described. The particular valve above referred to is included in the subject matter of application Ser. No. 599,450, now Patent No. 2,914,033, entitled Air Operated Tool and Valve There-for, filed July 23, 1956.

The ports 103 normally handle suflioient flow of fluid to allow for effective operation of the piston G during the work stroke of the tool. However, in order "to increase the rapidity of the work stroke by further elimination of back pressure, a. pressure relief valve 110 is provided. The valve 110 is spring biased to withstand the fluid pressure required to raise or return the piston G to the upper end of the cylinder 12, and it exhausts fluid when said pressure is exceeded.

From the foregoing it will be seen that I have provided a. fluid operated tool and piston construction therefor that is unique in construction and function. By employing the piston G above described in a tool of the character referred to, advantageous results are obtained. The large diameter piston body X is light in weight and is easily and rapidly accelerated and decelerated. Further, the m tion of the head Y and driver blade D is not affected at the end of the work stroke by damping or snubbing of the piston body X. With the structure that I provide the head Y and driver blade D are separately damped as a unit by either the driving of a staple or by the compression of the spring 75, or by both. Thus, the full effect of the fluid power employed is used to drive the head Y and blade D to the end of the work stroke, and after said work stroke is completed the means K acts to retraot the head Y and driver blade D so that the blade does not project from the head of the tool.

Having described only a typical preferred form and application of my invention, 1 do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art and fall the scope of the following claims:

Having described my invention, I claim:

1. A piston for accelerating a driver and adapted to be decelerated without aflecting the motion of said driver, including, a disc shaped body for operating in a cylinder and with a bottom, a cylindrical skirt depending from the bottom of the body, a driving head shiftably carried in said skirt and having a downwardly faced shoulder and with an upper face engageable with the bottom of the body to be driven in one direction thereby, a seat carried by the skint and having an opening passing the head, a retainer supporting the seat in the skirt, and means engaged between the said shoulder and seat yieldingly urging the face of the head into engagement with said bottom to be driven thereby, (the said 'head being coupled directly to the driver.

2. A tool of the character described including, an elongate cylinder, a disc shaped piston body for operation in the cylinder and with a bottom, a cylindrical skirt depending from the body, a driving head shifitably carried in said skirt and having a-downwardly faced shoulder and with a face engageable with the body to be driven in one direction thereby, a seat carried by the skirt and having an opening passing the head, a retainer supporting the seat in the skirt, a spring means engaged between the shoulder and the seat yieldingly urging the face of the head into engagement with said bottom of the body to be driven thereby, the said head being coupled directly to a driver, and a snubber at one endof the cylinder for damping the piston body independently of the head and driver.

References Cited in the file of this patent UNITED STATES PATENTS 2,585,941 Juilfs Feb. 19, 1952 2,707,277 Aldrich May 3, 1955 2,774,968 Osborne et a1 Dec. 25, 1956 2,818,570 Faccou Jan. 7, 1958 2,821,170 Jacobus Jan. 28, 1958 

1. A PISTON FOR ACCELERATING A DRIVE AND ADAPTED TO BE DECELERATED WITHOUT AFFECTING THE MOTION OF SAID DRIVER, INCLUDING, A DISC SHAPED BODY FOR OPERATING IN A CYLINDER AND WITH A BOTTOM, A CYLINDRICAL SHIRT DEPENDING FROM THE BOTTOM OF THE BODY, A DRIVING HEAD SHIFTABLY CARRIED IN SAID SKIRT AND HAVING A DOWNWRDLY FACED SHOULDER AND WITH AN UPPER FACE ENGAGEABLE WITH THE BOTTOM OF THE BODY TO BE DRIVEN IN ONE DIRECTION THEREBY, A SEAT CARRIED BY THE SKIRT AND HAVING AN OPENING PASSING THE HEAD, A RETAINER SUPPORTING THE SEAT IN THE SKIRT, AND MEANS ENGAGED BETWEEN THE SAID SHOULDER AND SEAT YIELDINGLY URGING THE FACE OF THE HEAD INTO ENGAGEMENT WITH SAID BOTTOM TO BE DRIVEN THEREBY, THE SAID HEAD BEING COUPLED DIRECTLY TO THE DRIVER. 